1. Field of the Invention
The present invention relates to a dispenser of a liquid product containing a film-forming polymer. More particularly, this dispenser is an aerosol dispenser comprising a container with a pressurized propellant gas, a dispensing nozzle, and a dispensing valve for actuating the dispensing of the product at will and for allowing this product to be delivered in the form of fine droplets or a mist.
In accordance with the invention, the product to be sprayed is an aqueous or hydroalcoholic composition containing at least one film-forming polymer. More particularly, this composition is a hair composition such as a lacquer for holding the hair, a brushing out lotion, a setting lotion, or a hair-styling solution.
2. Description of the Background
Conventionally, the hair compositions to be sprayed onto the hair are in essence constituted by an alcoholic or hydroalcoholic solution and a solubilized polymer, optionally in a mixture with various cosmetic adjuvants. Usually this solution is packaged either in a pump bottle or in an appropriate pressurized container.
For some years, particular interest has been shown in obtaining essentially aqueous cosmetic hair compositions. Indeed, the use of an alcohol such as ethanol or isopropanol on its own or in a mixture with a small proportion of water may have certain drawbacks, in particular inflammability.
Moreover, for economic and ecological reasons, attempts are increasingly being made to reduce the content of volatile organic compounds present in cosmetic compositions, mainly solvents such as ethanol, that are sprayed into the atmosphere.
To reduce the quantity of volatile compounds, an attempt has been made to replace by water the solvents such as ethanol. However, although most of the hydrosoluble film-forming polymers in an aqueous solution may lead to obtaining a composition for fixing the hair, they have major drawbacks. Thus the essentially aqueous solutions of these hydrosoluble polymers do not allow high degrees of fixation to be obtained. It has been proposed to use these hydrosoluble polymers in high concentrations, but an increase in their concentration produces such an increase in the viscosity of the compositions that satisfactory spraying can be obtained only with great difficulty. Even if correct spraying is obtained, these aqueous compositions have a particularly long drying-out time as compared with alcohol-based compositions, which gives them but little practical value.
It has also been proposed to use aqueous dispersions of insoluble particles of polymers, instead of solubilized polymers. However, to date, the results obtained have not yet been satisfactory. In particular, the Applicant has found that when one tries to use, in a conventional aerosol dispenser, high concentrations of polymers that are insoluble in the medium, in particular an aqueous medium, the quality of the spray is not satisfactory. The atomized liquid particles are not fine; frequently the spray is not diffuse and the dispensing is irregular. To avoid an excessive drying-out time of an aqueous dispersion, the Applicant has tried to reduce the delivery rate of the valve during the dispensing of the product. In these conditions, it has been found that the spraying nozzle and/or the dispensing valve frequently have a tendency to clog up. Moreover, the Applicant has noted the formation of foam round the spray opening which is prejudicial to the spraying quality. Moreover, this foam flows onto the container and dirties the user's fingers.
From EP-A-0 008 109, there is known a pressurized dispenser for the dispensing of a liquid product or of a dispersion of particles. This dispenser is provided with a valve comprising a main body and a prenuxing chamber provided with an additional gas intake. The product is passed into this chamber via a capillary dip tube. The chamber communicates with the valve body. The valve body can be caused to communicate with a spraying nozzle by operating an actuating stem that has for this purpose a passage opening obturated in the rest position. The delivery rate of the valve is determined by the cross-section of the capillary tube. According to this document, the inflammability of the product to be sprayed is reduced by using a valve with a premixing chamber.
Moreover, U.S. Pat. No. 3,653,553 discloses a dispenser with a sequential valve comprising an additional gas intake and provided with a premixing chamber. This valve is configured in such a way as to allow the dispensing ducts down the line from the valve to be purged by a jet of pure propellant gas. The valve is provided with an antechamber into which there leads an additional gas intake. A kneed duct obtained in the bottom portion of the actuating stem connects this antechamber to the internal space of the valve body. During a partial depression of the actuating stem, propellant gas penetrates into the antechamber, resulting in a drop in the internal pressure in the antechamber, so that any drawing-in of the product via a drawing-in duct is prevented. During the complete depression of the valve stem the duct is obturated by a projection of the stem so that a gas/product mixture can be dispensed. During this complete depression, the internal space of the antechamber is occupied substantially completely by the lower portion of the stem, so that in the dispensing position, this antechamber is substantially non-existent. In other words, in the dispensing position, this valve has almost no antechamber. With such a device, the problem of the presence of foam in the upper portion of the device (in particular round the spray opening) occurs to a substantial extent.
Furthermore, BE-A-664 905 describes a valve of the same kind. At the bottom of the valve body, there is provided an opening for the intake of the product, leading into a premixing chamber provided with an additional gas intake. The premixing chamber is separated from the main valve chamber by an elastomeric partition which is traversed by a passage opening. During the actuation of this valve, the elastomeric partition is pushed towards the bottom of the valve body, so that the premixing chamber becomes virtually non-existent. The problems posed by such a device are identical with those described with reference to U.S. Pat. No. 3,653,553.
Since the correct atomization is an essential element for the final quality of the application of a hair composition to be sprayed onto the hair, it is of the utmost importance to remedy these drawbacks to obtain a good quality spray with fine particles and a good spread of the spray over the head of hair as a whole.